From: "Nadolski, Edmund" <edmund.nadolski@intel.com>
To: Keith Busch <kbusch@kernel.org>,
linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me
Subject: Re: [PATCH] nvme/pci: Remove last_sq_tail
Date: Thu, 5 Dec 2019 13:31:20 -0700 [thread overview]
Message-ID: <149bb39b-e8ab-36a5-f319-18ef5e3567b6@intel.com> (raw)
In-Reply-To: <20191205200825.27651-1-kbusch@kernel.org>
On 12/5/2019 1:08 PM, Keith Busch wrote:
> We don't allocate enough tags to wrap the submission queue. Remove
> tracking for this condition.
Can we ensure that this presumption won't change?
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
> drivers/nvme/host/pci.c | 20 ++++----------------
> 1 file changed, 4 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 0590640ba62c..3acd1b4d7735 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -174,7 +174,6 @@ struct nvme_queue {
> u16 q_depth;
> u16 cq_vector;
> u16 sq_tail;
> - u16 last_sq_tail;
> u16 cq_head;
> u16 qid;
> u8 cq_phase;
> @@ -462,21 +461,11 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
> /*
> * Write sq tail if we are asked to, or if the next command would wrap.
Comment needs to be updated.
Ed
> */
> -static inline void nvme_write_sq_db(struct nvme_queue *nvmeq, bool write_sq)
> +static inline void nvme_write_sq_db(struct nvme_queue *nvmeq)
> {
> - if (!write_sq) {
> - u16 next_tail = nvmeq->sq_tail + 1;
> -
> - if (next_tail == nvmeq->q_depth)
> - next_tail = 0;
> - if (next_tail != nvmeq->last_sq_tail)
> - return;
> - }
> -
> if (nvme_dbbuf_update_and_check_event(nvmeq->sq_tail,
> nvmeq->dbbuf_sq_db, nvmeq->dbbuf_sq_ei))
> writel(nvmeq->sq_tail, nvmeq->q_db);
> - nvmeq->last_sq_tail = nvmeq->sq_tail;
> }
>
> /**
> @@ -493,7 +482,8 @@ static void nvme_submit_cmd(struct nvme_queue *nvmeq, struct nvme_command *cmd,
> cmd, sizeof(*cmd));
> if (++nvmeq->sq_tail == nvmeq->q_depth)
> nvmeq->sq_tail = 0;
> - nvme_write_sq_db(nvmeq, write_sq);
> + if (write_sq)
> + nvme_write_sq_db(nvmeq);
> spin_unlock(&nvmeq->sq_lock);
> }
>
> @@ -502,8 +492,7 @@ static void nvme_commit_rqs(struct blk_mq_hw_ctx *hctx)
> struct nvme_queue *nvmeq = hctx->driver_data;
>
> spin_lock(&nvmeq->sq_lock);
> - if (nvmeq->sq_tail != nvmeq->last_sq_tail)
> - nvme_write_sq_db(nvmeq, true);
> + nvme_write_sq_db(nvmeq);
> spin_unlock(&nvmeq->sq_lock);
> }
>
> @@ -1511,7 +1500,6 @@ static void nvme_init_queue(struct nvme_queue *nvmeq, u16 qid)
> struct nvme_dev *dev = nvmeq->dev;
>
> nvmeq->sq_tail = 0;
> - nvmeq->last_sq_tail = 0;
> nvmeq->cq_head = 0;
> nvmeq->cq_phase = 1;
> nvmeq->q_db = &dev->dbs[qid * 2 * dev->db_stride];
>
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next prev parent reply other threads:[~2019-12-05 20:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-05 20:08 [PATCH] nvme/pci: Remove last_sq_tail Keith Busch
2019-12-05 20:31 ` Nadolski, Edmund [this message]
2019-12-05 20:48 ` Keith Busch
2019-12-12 9:20 ` Christoph Hellwig
2019-12-12 15:47 ` Keith Busch
2019-12-12 20:11 ` Sagi Grimberg
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